Study On The Processing Of Si/Cu Surface Of Micro-nano-precision By Using Quasicontinuum Method

As the development of Micro-electronics and Microsystems, researchers pay much attention on the micro-mechanical of materials. In micro-nanofabrication, chip removal takes place in a limited region containing only a few atoms or atomic layers. So some phenomena including energy dissipation, machined surface formation and chip removal, and so on, differ from those of general grinding process. Because micro-components always show different characteristics from components in macro-scale, the microcosmic mechanism of deformation is important to study the properties of material in micro-scale. However, traditional methods based on continuum theories do not work in investigating the mechanism of micro-deformation, and microcosmic methods such as Molecular Dynamics can not be used to simulate the deformation of a large region in common personal computers for its large computation memory caused by large degrees of freedom. In this situation, researchers pay much attention on the the multi-scale methods coupling atomistic scale and continuum scale.The Quasicontinuum Method is developed as a typical multi-scale method. The key idea is that of selective representation of atomic degrees of freedom. Instead of treating all atoms making up the system, a small relevant subset of atoms is selected to represent, by appropriate weighting, the energetics of the system as a whole. Based on their kinematic environment, the energies of individual "representative atoms" are computed either in nonlocal fashion in correspondence with straightforward atomistic methodology or within a local approximation as befitting a continuum model. Then, the QC uses continuum assumptions to reduce the degrees of freedom and computational demand without losing atomistic detail in regions where it is required.In this paper, the Quasi-continuum Method was used to simulate the micro-nanofabrication process of copper and silicon. The model included the utilization of Stillinger-weber potential to simulate the interatomic force between silicon atoms, and the EAM potectial between copper atoms. The law of surface atoms interaction deformation and fracture is obtained in the micro-nanofabrication process under different conditions by simulation. It is concluded the technical measures which taken in process of Si/Cu surface of micro-nano-precision. Simulation results shows that, in the process of micro-nanofabrication the maximum load varies linearly with the aspect ratio. According to the certain relation (see eqn.(4.3) and (4.4)) between the maximum load and the product of residual atomic layers and aspect ratio, it can attain perfect polished result, and the residual atomic layers and aspect ratio satisfy certain relations (see eqn.(4.5) and (4.6)). In the process of Si/Cu composite polishing, the surface should been polished with high load at first, then reduce the polishing load when the surface of silicon meet the requirement. The study of this paper shows that, it has significant meaning for researching the micro-nanofabrication process on Quasi-continuum Method.